Study on the toxical sensitivity of uterus of pregnant mouse by using TCDD
妊娠小鼠子宫对2,3,7,8-四氯苯二噁英毒性的敏感性研究

The distribution of TCDD in tissue is key important for investigation of TCDD caused early embryo loss of pregnant mouse. By using a newly established yeast gene report system, TCDD content in liver, kidney, brain, fat, uterus and embryo of pregnant mouse were analyzed after had been taken different dosage of TCDD orally. The results showed that fat tissue accumulated highest amount of this toxin; liver, uterus and embryo also accumulated high concentration of TCDD from high to low. Since TCDD needed to be activated by its induced enzyme including cytochrome P450 1A2, the levels of enzyme were tested using immunohistochemical assay in different toxicity treatment. The highest signal was observed in liver and uterus, even in low dosage treatment, implying that uterus was an important sensitive target tissue of TCDD toxin. Positive signals were observed in kidney and fat at high dosage group, and only few cells in brain tissue could show the weak signals. These results implied that uterus was another TCDD metabolizing organ similar to liver, in which TCDD was converted into activating forms by cytochrome P450 1A2 enzyme. The high accumulation of TCDD in uterus, as well as high sensitivity for inducing cytochrome P450 1A2 enzyme mediated by AhR in uterus could explain the reason of early embryo loss in pregnant mouse at low dosage treatment.